PDBsum entry: 1kxh

Hydrolase

PDB-id: 1kxh

Contents

Description

Header details

Header records

References

PROCHECK

Protein chain

448 a.a. *

Ligands

ACR

Metal ions

_CL

_CA

Waters ×205

* Residue conservation analysis

Tools

Clefts Calculation

PDB id:

1kxh

Name:

Hydrolase

Title:

Crystal structure of the complex between an inactive mutant of psychrophilic alpha-amylase (d174n) and acarbose

Structure:

Alpha-amylase. Chain: a. Engineered: yes. Mutation: yes

Source:

Pseudoalteromonas haloplanktis. Organism_taxid: 228. Expressed in: escherichia coli. Expression_system_taxid: 562

UniProt:

P29957 (AMY_PSEHA)

Seq:

Struc:

Seq:

Struc:

Seq:

669 a.a.

Struc:

448 a.a.*

Key:	PfamA domain
Secondary structure	CATH domain

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme class:

E.C.3.2.1.1   [IntEnz]   [ExPASy]   [KEGG]   [BRENDA]

Reaction:

Endohydrolysis of 1,4-alpha-glucosidic linkages in oligosaccharides and polysaccharides.

Resolution:

2.30Å

R-factor:

0.138

R-free:

0.188

Authors:

N.Aghajari,R.Haser

Key ref:

N.Aghajari et al. (2002). Crystallographic evidence of a transglycosylation reaction: ternary complexes of a psychrophilic alpha-amylase.. Biochemistry, 41, 4273-4280. [PubMed id: 11914073] [DOI: 10.1021/bi0160516]

Date:

31-Jan-02

Release date:

19-Jun-02

Related entries:

1g94
complex native aha/acarbose/tris
1g9h
complex native aha/component ii/tris
1aqh
native structure of wildtype aha
1aqm
complex native aha/tris
1boi
native structure of recombinant aha

Quick_links

Procheck

Clefts

Surface

Key reference

DOI no: 10.1021/bi0160516

Biochemistry 41:4273-4280 (2002)

PubMed id: 11914073

Crystallographic evidence of a transglycosylation reaction: ternary complexes of a psychrophilic alpha-amylase.

N.Aghajari, M.Roth, R.Haser.

ABSTRACT

The psychrophilic Pseudoalteromonas haloplanctis alpha-amylase is shown to form ternary complexes with two alpha-amylase inhibitors present in the active site region, namely, a molecule of Tris and a trisaccharide inhibitor or heptasaccharide inhibitor, respectively. The crystal structures of these complexes have been determined by X-ray crystallography to 1.80 and 1.74 A resolution, respectively. In both cases, the prebound inhibitor Tris is expelled from the active site by the incoming oligosaccharide inhibitor substrate analogue, but stays linked to it, forming well-defined ternary complexes with the enzyme. These results illustrate competition in the crystalline state between two inhibitors, an oligosaccharide substrate analogue and a Tris molecule, bound at the same time in the active site region. Taken together, these structures show that the enzyme performs transglycosylation in the complex with the pseudotetrasaccharide acarbose (confirmed by a mutant structure), leading to a well-defined heptasaccharide, considered as a more potent inhibitor. Furthermore, the substrate-induced ordering of water molecules within a channel highlights a possible pathway used for hydrolysis of starch and related poly- and oligosaccharides.